U.S. Geological Survey
2018
Seismic Reflection, EdgeTech SB-512i chirp profile images,USGS field activity 2017-003-FA, Mississippi River Delta front offshore of southeastern Louisiana (PNG images)
1.0
raster digital data
data release
DOI:10.5066/F7X929K6
Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts
U.S. Geological Survey, Coastal and Marine Geology Program
https://doi.org/10.5066/F7X929K6
https://www.sciencebase.gov/catalog/item/5a958874e4b06990606a7cc8
Wayne E. Baldwin
Seth D. Ackerman
Charles R. Worley
William W. Danforth
Jason D. Chaytor
2018
High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA
1.0
data release
DOI:10.5066/F7X929K6
Reston, VA
U.S. Geological Survey
Suggested citation: Baldwin, W.E., Ackerman, S.D., Worley, C.R., Danforth, W.W., and Chaytor, J.D, 2018, High-resolution geophysical data collected along the Mississippi River Delta front offshore of southeastern Louisiana, U.S. Geological Survey Field Activity 2017-003-FA: U.S. Geological Survey data release, https://doi.org/10.5066/F7X929K6.
https://doi.org/10.5066/F7X929K6
https://www.sciencebase.gov/catalog/item/5a8c4bcbe4b00f54eb44044c
High resolution bathymetric, sea-floor backscatter, and seismic-reflection data were collected offshore of southeastern Louisiana aboard the research vessel Point Sur on May 19-26, 2017, in an effort to characterize mudflow hazards on the Mississippi River Delta front. As the initial field program of a research cooperative between the U.S. Geological Survey, the Bureau of Ocean Energy Management, and other Federal and academic partners, the primary objective of this cruise was to assess the suitability of sea-floor mapping and shallow subsurface imaging tools in the challenging environmental conditions found across delta fronts (for example, variably distributed water column stratification and widespread biogenic gas in the shallow subsurface). Approximately 675 kilometers (km) of multibeam bathymetry and backscatter data, 420 km of towed chirp data, and 550 km of multichannel seismic data were collected. Varied mudflow (gully, lobe), prodelta morphologies, and structural features were imaged in selected survey areas from Pass a Loutre to Southwest Pass.
These PNG images represent approximately 420 km of chirp seismic-reflection data collected by the U.S. Geological Survey during cruise 2017-003-FA along the Mississippi River Delta front offshore of southeastern Louisiana. Images of each seismic profile were generated in order to provide portable and easily viewable alternatives to the SEGY versions of the data. Each profile image can be hotlinked to its corresponding trackline navigation contained within the Esri polyline shapefile '2017-003-FA_512i_Tracklines.shp'. Shotpoint index marks along the top of the PNG images correlate to the positions of 500 shot intervals within the Esri point shapefile '2017-003-FA_512i_500sht.shp'.
Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-003-FA.
20170521
20170524
ground condition
None planned.
-89.554864
-88.862675
29.285489
28.775983
USGS Metadata Identifier
USGS:5a958874e4b06990606a7cc8
None
U.S. Geological Survey
USGS
Woods Hole Coastal and Marine Science Center
WHCMSC
Coastal and Marine Geology Program
CMGP
Bureau of Ocean Energy Management
BOEM
field activity number 2017-003-FA
seismic profile
seismic reflection
chirp
Edgetech
512i
image
PNG
Marine Geology
ISO 19115 Topic Category
oceans
geoscientificInformation
USGS Thesaurus
seismic reflection methods
sub-bottom profiling
marine geophysics
marine geology
None
Gulf of Mexico
Southeast Louisiana
Mississippi River Delta Front
Southwest Pass
South Pass
Pass a Loutre
None
sea floor
seafloor
none
2017
None
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
U.S. Geological Survey
Wayne E. Baldwin
Geologist
mailing and physical
384 Woods Hole Road
Woods Hole
Massachusetts
02543-1598
US
508-548-8700 x2226
508-457-2310
wbaldwin@usgs.gov
https://www.sciencebase.gov/catalog/file/get/5a958874e4b06990606a7cc8/?name=2017-003-FA_512i_Images_browse.jpg
Thumbnail image of chirp seismic-reflection profile example from the Mississippi River Delta front offshore of southeastern Louisiana.
JPEG
Processed seismic data were converted to PNG format for ease of seismic trace display. Quality control was conducted during processing.
Sections of tracklines where navigation was recorded but no seismic data were logged are not included such as during testing, some turns, and very short files. There are no Line-0001, Line-0004, Line-0016 or Line-0017.
Although navigation is not stored in the images, positional accuracy is relevant to the accuracy of these data. The EdgeTech SB-0512i subbottom profiler was mounted on a catamaran sled and towed at the sea surface approximately 40 m astern of the M/V Scarlett Isabella. The transducer depth below water line was 0.5 meters below catamaran floats. Navigation data for the 512i were collected using a Wide Area Augmentation System (WAAS) enabled Garmin Differential GPS (DGPS) receiver, which was located on the catamaran sled and connected to the acquisition computer via a serial cable. Positioning data were recorded in SonarWiz (version 6.05.0011) acquisition software, which logged positioning coordinates to individual trace headers SEG-Y format. WAAS enabled GPS horizontal positional accuracy is assumed to be within 2 m; however, horizontal position uncertainty increases with sonar and sled motion, which was not compensated for at the sonar transducer.
U.S. Geological Survey
Unpublished Material
512i PNG image data
raster digital data
disc
20170521
20170524
ground condition
SEG-Y 512i data
Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-0512i towfish (0.5-12 kHz), which was mounted on a catamaran and towed astern of the R/V Point Sur of Gulfport, MS. Chesapeake Technology's SonarWiz (version 6.05.0011) seismic acquisition software was used to control the Geo-Star topside unit, digitally log trace data in the SEG-Y Rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arc seconds of Latitude and Longitude, multiplied by a scalar of 100). Data were acquired using shot rates between 250 and 750 milliseconds (ms), a 30-ms pulse length, and a 0.5 to 7.2 kHz frequency sweep. Traces were recorded with a 46-microsecond sample interval over lengths between approximately 180 and 700 ms.
Scripts within SIOSEIS (version 2015.3.1) and Seismic Unix (version 4.2) were used to process SEG-Y data, create navigation files, and plot images. The processing flow and scripts used to produce navigation files including trackline shapefiles are summarized below and in the following processing steps.
1) SIOSEIS (version 2015.3.1) was used to read SEG-Y files, renumber shots starting from one, extract the envelope-detected trace, and write out new SEG-Y files. The original shot numbers, which were assigned by SonarWiz sequentially over the duration of an acquisition session despite SEG-Y file changes, are preserved in the raw SEG-Y data.
2) The SIOSEIS script Sio_medianstk was used to minimize cross talk from the multichannel seismic acquisition sources (boomer and sparker) with a two-trace median stack (trim 50 percent of the values furthest from the median amplitude) and improve water bottom picking. This script was used for all lines even when multi-channel acquisition was not simultaneously occurring, due to the improvements made to water bottom picks.
3) The script Read512i_mstk was used to read median filtered stacked and renumbered SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, latitude, year, Julian day, and time of day (UTC). Header information from each SEG-Y file was saved to text files after an AWK (no version) filter was used to maintain the first and last shots, shots at multiples of 100, 500, and shots with unique navigation coordinates. Geographic coordinates (WGS 84) were converted to UTM zone 16 N coordinates (WGS 84) using Proj (version 4.6.0). End shots and shots at multiples of 100 may not have unique navigation coordinates. Separate text files containing the first and last shots and even 500 shot intervals were also saved. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile images. Read512i_mstk called a Python script 512itoSQL17003.py, written by Wayne Baldwin, which imported the CSV files to a Spatialite (version 4.3.0) enabled SQLite (version 3.21.0) database.
4. The SIOSEIS script siothresh_pltwbt was used to pick the water-bottom time from the median stacked SEG-Y files, apply a swell filter to smooth water-bottom time picks and shift the trace data by the difference between the smoothed and unsmoothed water bottom time before writing the shifted trace data to a new SEG-Y file.
5. The Seismic Unix script Plot512i_s creates a swell-filtered PNG image using ImageMagick (version 6.9.5-4) of each seismic line that is 12 inches high. Images show two-way travel time (seconds) along the y-axis (left margin) and shots along profile (labeled at 500 shot intervals) on the x-axis (along top of profile).
201712
Wayne E. Baldwin
U.S. Geological Survey
Geologist
mailing and physical address
384 Woods Hole Rd.
Woods Hole
MA
02543-1598
(508) 548-8700 x2226
(508) 457-2310
wbaldwin@usgs.gov
Added keywords section with USGS persistent identifier as theme keyword.
20200807
U.S. Geological Survey
VeeAnn A. Cross
Marine Geologist
Mailing and Physical
384 Woods Hole Road
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
Raster
Pixel
The PNG seismic reflection images can be hyperlinked to their corresponding trackline or shotpoint locations in ArcGIS using the shapefiles '2017-003-FA_512i_Tracklines.shp' or '2017-003-FA_512i_500sht.shp', respectively (available from the larger work citation). The images show two-way travel time (seconds) on the y-axis and distance along profile (annotation at 500 shot intervals) on the x-axis.
U.S. Geological Survey
U.S. Geological Survey - ScienceBase
mailing and physical address
Federal Center
Building 810
Mail Stop 302
Denver
CO
80225
1-888-275-8747
USGS data release 2017-003-FA 512i PNG imagery from the Mississippi River Delta front area: includes the zip archive 2017-003-FA_512i_Images.zip containing 55 PNG images named according to line convention with an '_s' appended to note swell-filter processing, the browse graphic 2017-003-FA_512i_Images_browse.jpg, and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2017-003-FA_512i_Images_meta.xml.
Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
PNG
ImageMagick (version 6.9.5-4)
Portable Network Graphic (PNG)
The 7zip (version 16.04) file contains seismic-reflection profile images of EdgeTech SB-512i collected by the U.S. Geological Survey - Woods Hole Coastal and Marine Science Center along the Mississippi River Delta front and the associated metadata.
Use WinZip, 7zip, Peazip or pkUnzip
520
https://www.sciencebase.gov/catalog/item/5a958874e4b06990606a7cc8
https://www.sciencebase.gov/catalog/file/get/5a958874e4b06990606a7cc8
https://doi.org/10.5066/F7X929K6
The first link is to the page containing the data, the second link downloads all data available from the page as a zip file, and the third link is to the publication landing page.
none
These data can be viewed with any PNG image viewing software. The zip files must be uncompressed in order to view the images.
20200807
U.S. Geological Survey
Wayne E. Baldwin
Geologist
mailing and physical
384 Woods Hole Rd.
Woods Hole
MA
02543-1598
(508) 548-8700 x2226
(508) 457-2310
wbaldwin@usgs.gov
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time